JP2008264217A - Hemodialysis evaluation method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a hemodialysis evaluation method that determines in high precision the capacity of biologic body fluid containing urea, as this method is hard to be affected by the physiological changes, etc. of a patient during hemodialysis treatment, and consequently the method evaluates the hemodialysis results from the standardized dialysis volume Kt/V, a hemodialysis index, determined in high precision. <P>SOLUTION: The method concerns a hemodialysis evaluation method used in the hemodialysis treatment with an artificial kidney for evaluating hemodialysis results from the standardized hemodialysis volume Kt/V. In the term of standardized hemodialysis volume Kt/V, K is the clearance value of a dialyzer (ml/mm/kg), t is dialysis time and V is the capacity of body fluid containing urea. For determining the standardized dialysis volume Kt/V, the capacity V of body fluid containing urea is measured by a biologic body electric impedance method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hemodialysis evaluation method and a hemodialysis evaluation apparatus for evaluating a dialysis result in hemodialysis, and more particularly to a hemodialysis evaluation method and a hemodialysis evaluation apparatus using a standardized dialysis amount Kt / V.

  As an index for evaluating hemodialysis with an artificial kidney, a standardized dialysis amount Kt / V is used. K is the clearance value of the dialyzer of the artificial kidney, t is the dialysis time, and V is the volume of the portion where urea can be distributed in the dialysis patient. Since urea is usually present in body fluids such as blood, V is the volume of the urea-distributed body fluid.

  When the standardized dialysis amount Kt / V is increased, hemodialysis is sufficiently performed and the risk of death is reduced. In the Japanese Society for Dialysis Therapy, the ideal standardized dialysis dose Kt / V is 1.6 or more, and in reality, 1.2 or more is considered preferable.

  By the way, when actually evaluating dialysis with the standardized dialysis amount Kt / V, it is difficult to directly measure the urea removal amount of the dialyzer, the dialysis time t, and the volume of the urea distribution body fluid of the dialysis patient. For this reason, the body is considered to be a simplified container, and the standardized dialysis amount Kt / V has been obtained focusing only on the removal of urea. However, during dialysis, urine is produced and the volume of body fluid is reduced. That is, since it is physiologically affected, the dialysis evaluation can be accurately performed with Kt / V obtained only from the clearance value K, the dialysis time t, and the volume V of the urea distribution body fluid obtained from the body weight. It turns out that it can't be done.

  Therefore, in order to solve the above problems, a hemodialysis evaluation method described in Patent Document 1 below has been proposed. In the hemodialysis evaluation method described in Patent Document 1, in the hemodialysis evaluation method using Kt / V, a method of evaluating the first hemodialysis result in a week using Kt / V obtained by the following formula (A) Is disclosed.

  In the formula (A), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using the following formula (B). Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml), IBW is ideal body weight (kg).

  Patent Document 1 discloses a method using Kt / V obtained by the following equation (C) as a method for evaluating the second hemodialysis result in a week.

  In the formula (C), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the second dialysis in the week. The value obtained by dividing the post-plasma urea nitrogen concentration by the two pre-dialysis plasma urea nitrogen concentrations, UF is the total limit filtration volume (ml) during the second hemodialysis in the week, and IBW is the ideal body weight (kg) It is.

Japanese Patent Laid-Open No. 11-137666

  In the hemodialysis evaluation method described in Patent Document 1, the first and second hemodialysis evaluations in a week can be performed with higher accuracy by compensating for physiological fluctuations and the like during dialysis. However, the hemodialysis evaluation method described in Patent Document 1 is established on the assumption that the following 1) to 6) are satisfied.

  1) Dialysis patients receive hemodialysis treatment 3 times a week.

  2) The dialysis times for all hemodialysis weeks are equal.

  3) No residual renal function.

  4) Urea plasma nitrogen concentration (BUN) should be measured before or after the first or second hemodialysis week.

  5) Assuming that the cardiac blood output (CO) is constant at 70 ml / min / kg both during and outside dialysis, the blood flow rate of blood access is constant at 11 ml / min / kg.

  6) The urea distribution volume per unit ideal body weight should be 670 ml / kg.

  That is, based on the assumption that the items 1) to 6) are satisfied, the first and second hemodialysis evaluations of the week are performed using the above formulas (A) and (C).

  By the way, among the items 1) to 6) above, 6) relates to the Vt of Kt / V, that is, the volume of the urea-distributed body fluid in which urea is distributed in the body of the dialysis patient. ), When the ideal weight is IBW, 670 × IBW, and the right side of the formula (C) also corresponds to the portion indicated by 670 × IBW. That is, the ideal body weight of the dialysis patient is fixed, the urea distribution volume per unit ideal body weight is 670 ml / kg, and the right side of the formulas (C) and (D), the 670 × IBW present in the molecule gives the urea distribution body fluid The volume V is obtained. According to this method, the volume V of the urea distribution body fluid can be easily obtained simply by measuring the weight of the dialysis patient.

  However, since the volume V of the urea distribution body fluid is obtained based on the body weight, Kt / V obtained on the right side of the formulas (C) and (D) is unlikely to be an accurate value.

  In addition, the weight of dialysis patients varies greatly during dialysis. That is, during hemodialysis using a dialyzer, not only is urea removed, but also water is removed by ultrafiltration, so the amount of body water varies greatly. Therefore, in the method of obtaining the volume V of the urea distribution body fluid based on the body weight, the volume V of the urea distribution body fluid cannot be obtained accurately and the fluctuation cannot be followed.

  Therefore, an object of the present invention is to obtain the volume V of the urea distribution body fluid with higher accuracy, and therefore, it is possible to evaluate the standard dialysis amount Kt / V that is an index of hemodialysis with higher accuracy. To provide a hemodialysis evaluation method and a hemodialysis evaluation apparatus.

  According to the present invention, there is provided a hemodialysis evaluation method for evaluating hemodialysis results using a standardized dialysis amount Kt / V in hemodialysis using an artificial kidney, wherein K is a dialyzer in the standardized dialysis amount Kt / V. Clearance value (ml / mm / kg), t is the dialysis time, V is the volume of the urea distribution body fluid, and when obtaining the standardized dialysis amount Kt / V, the volume V of the urea distribution body fluid There is provided a hemodialysis evaluation method characterized by measuring using an electrical impedance method.

  In a specific aspect of the present invention, the volume V of the urea distribution body fluid is the body water amount TBW measured by the bioelectric impedance method, and therefore, the body water amount TBW is measured using the bioelectric impedance method. Thus, an amount corresponding to the volume V of the urea distribution volume of the dialysis patient can be immediately obtained with high accuracy.

  Further, in another specific aspect of the hemodialysis evaluation method of the present invention, in evaluating the initial dialysis result in the week based on the standardized dialysis amount Kt / V, a clearance value is defined as K on the right side of the following formula (1). , Dialysis time as TD, and body water content measured by bioelectrical impedance method as TBW.

  In equation (1), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using equation (B) below, TD is Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml).

  In another specific aspect of the hemodialysis evaluation method according to the present invention, when evaluating the second hemodialysis result in the week by the standardized dialysis amount Kt / V, K on the right side of the following formula (2) As the clearance value, TD as the dialysis time, and TBW as the body water content measured by the bioelectrical impedance method.

  In equation (2), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the plasma after the second dialysis in the week It is a value obtained by dividing the urea nitrogen concentration by the two pre-dialysis plasma urea nitrogen concentrations, and UF is the total limit filtration volume (ml) during the second hemodialysis in a week.

  As described above, in order to evaluate the results of the first or second hemodialysis in the week using the formula (1) or (2), it is only necessary to measure the extracellular fluid volume ECW by the bioelectrical impedance method. The first and second hemodialysis evaluations can be performed with higher accuracy.

  In still another specific aspect of the hemodialysis evaluation method according to the present invention, the volume V of the urea distribution body fluid is an extracellular water amount ECW × 3 measured by the bioelectric impedance method, and therefore, by the bioimpedance method. The amount corresponding to the volume V of the urea-distributed body fluid can be immediately determined with high accuracy simply by determining the extracellular body fluid amount ECW and multiplying this three times.

  In still another specific aspect of the hemodialysis evaluation method according to the present invention, in evaluating the initial dialysis result in the week by the standardized dialysis amount Kt / V, a clearance value is set as K on the right side of the following formula (3). The dialysis time is used as TD, and the amount of extracellular body fluid measured by the bioelectrical impedance method is used as ECW.

  In equation (3), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using equation (B) below, where TD is Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml).

  In still another specific aspect of the hemodialysis evaluation method according to the present invention, when the second hemodialysis result in the week is evaluated based on the standardized dialysis amount Kt / V, the clearance is set as K on the right side of the following formula (4). The value is TD, dialysis time is used, and ECW is the amount of extracellular water measured by the bioelectrical impedance method.

  In equation (4), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the plasma after the second dialysis in the week It is a value obtained by dividing the urea nitrogen concentration by the two pre-dialysis plasma urea nitrogen concentrations, and UF is the total limit filtration volume (ml) during the second hemodialysis in a week.

  As described above, in order to evaluate the results of the first or second hemodialysis in the week using the formula (3) or (4), it is only necessary to measure the extracellular fluid volume ECW by the bioelectrical impedance method. The first and second hemodialysis evaluations can be performed with higher accuracy.

  In the hemodialysis evaluation method according to the present invention, a multifrequency bioelectrical impedance method is preferably used as the bioelectrical impedance method. In this case, a relatively low frequency current and a relatively high frequency current are used. The amount of liquid inside and outside the cell can be detected easily and with high accuracy by flowing and in vivo electrical impedance.

  That is, a high-frequency current of about several hundred kHz or more passes through the cell, but a low-frequency current lower than that of about several kHz or less hardly passes through the cell. Therefore, the amount of extracellular fluid ECW can be obtained by flowing a low-frequency current, and the amount of water in the cell can be measured by the impedance difference between the two. Hemodialysis can be evaluated.

  The hemodialysis evaluation apparatus according to the present invention includes a body fluid amount measuring means for measuring body water amount TBW or extracellular water amount ECW of a dialysis patient using a bioelectrical impedance method, and blood urea nitrogen level before and after dialysis of the dialysis patient. And the input means for inputting the dialysis time, the blood urea nitrogen value before and after dialysis input from the input means, the dialysis time, and the body water amount TBW or the extracellular water amount ECW obtained by the body fluid amount measuring means. And calculating means for storing V of the standardized dialysis amount Kt / V.

  In the hemodialysis evaluation apparatus according to the present invention, preferably, the bodily fluid amount measuring means measures the body water amount TBW or the extracellular fluid amount ECW by a multi-frequency bioelectrical impedance method. In this case, that is, a high-frequency current of several hundred kHz or more passes through the cell, but a low-frequency current lower than that of several hundred kHz or less hardly passes through the cell. Therefore, the amount of extracellular fluid ECW can be obtained by flowing a low-frequency current, and the amount of water in the cell can be measured by the impedance difference between the two. Hemodialysis can be evaluated.

  In the hemodialysis evaluation method according to the present invention, in obtaining the standardized dialysis amount Kt / V, the volume V of the urea distribution body fluid is measured using a bioelectrical impedance method. The value measured by the bioelectrical impedance method is highly correlated with the actual body water content and extracellular water content of dialysis patients, and therefore more than the volume of urea distribution body fluid estimated from the conventional body weight. Is accurate. In addition, since physiological changes during actual patient dialysis are also reflected, according to the present invention, the standardized dialysis amount Kt / V can be determined with higher accuracy, and thus the hemodialysis results can be improved. It becomes possible to evaluate to accuracy.

  Therefore, since the therapeutic effect of a dialysis patient can be determined more accurately, the effect of dialysis can be further enhanced.

  In the hemodialysis evaluation apparatus according to the present invention, the body fluid amount TBW or the extracellular water amount ECW of the dialysis patient is measured by the bioelectrical impedance method in the body fluid amount measuring means, and the blood urea nitrogen is measured in the computing means. The standardized dialysis amount Kt / V is obtained by the computing means from the value, the dialysis time, and the body water amount TBW or the extracellular water amount ECW obtained by the body fluid amount measuring means. According to the bioelectrical impedance method, the actual body water amount TBW or extracellular water amount ECW of a dialysis patient can be measured with high accuracy, so that the blood of the present invention can be obtained using the hemodialysis evaluation apparatus according to the present invention. By performing the dialysis evaluation method, the standardized dialysis amount Kt / V can be obtained with higher accuracy, and thereby hemodialysis can be evaluated with higher accuracy.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a schematic configuration diagram for explaining a hemodialysis evaluation method according to an embodiment of the present invention. As shown in FIG. 1, an artificial kidney device 2 and a hemodialysis evaluation device 3 are connected to a dialysis patient X.

  The artificial kidney device 2 has a dialyzer 4. The dialyzer 4 and the dialysis patient X are connected by dialysis tubes 5 and 6. The dialysis tube 5 connects the outlet port of the dialyzer 4 and the blood vessel of the dialysis patient X, and the dialysis tube 6 connects the blood vessel of the dialysis patient X and the inlet port of the dialyzer 4. A dialysate supply line and a dialysate discharge line are connected to the dialyzer 4, and the dialysate discharge line is connected to a drain pipe 7. The artificial kidney device 2 incorporates various devices for monitoring the state during dialysis, for example, the pressure of the dialysate. In the present embodiment, the artificial kidney device 2 is configured separately from the hemodialysis evaluation device 3, but may be configured integrally with the hemodialysis evaluation device 3.

  The hemodialysis evaluation apparatus 3 of this embodiment is an apparatus for obtaining a standardized dialysis amount Kt / V for evaluating hemodialysis in the artificial kidney apparatus 2.

  A schematic configuration of the hemodialysis evaluation apparatus 3 is shown in a block diagram in FIG.

  As shown in FIG. 2, the hemodialysis evaluation apparatus 3 has a keyboard 8 as input means. The blood urea nitrogen value before and after dialysis and the dialysis time are input from the keyboard 8. The blood urea nitrogen value before dialysis and the blood urea nitrogen value after dialysis are obtained by collecting and analyzing blood from the dialysis patient X before and after dialysis. For this analysis, an automatic analyzer or the like may be used, or measurement may be performed by a technique. In any case, the blood urea nitrogen value before dialysis, the blood urea nitrogen value after dialysis, and the dialysis time are input from the keyboard 8.

  The input means is not limited to the keyboard 8, and various input means such as a tablet input device can be used.

  The hemodialysis evaluation apparatus 3 has a CPU 9 to which the keyboard 8 is connected. Information input from the keyboard 8 is given to the CPU 9. In the CPU 9, a measurement processing unit 10 is connected. The measurement processing unit 10 sends the probe current Ia to the dialysis patient X as a measurement signal, thereby processing the voltage / current information obtained from the body of the dialysis patient X, and the body water amount TBW or the extracellular water amount ECW of the dialysis patient X. The electrical signal corresponding to is output. The CPU 9 is connected to the measurement processing unit 10 so that the measurement processing unit 10 starts measurement by the bioelectrical impedance method and receives a signal obtained from the measurement processing unit 10. A RAM 11 and a ROM 12 are connected to the CPU 9. The ROM 12 stores a program for calculating the body water content TBW and the extracellular water content ECW by the bioelectrical impedance method by the measurement processing unit 10, and an expression for calculating a standardized hemodialysis amount Kt / V described later. Yes.

  The RAM 11 is a data area for temporarily storing various data such as dialysis time input from the keyboard 8, blood urea nitrogen values before and after dialysis, and body water amount TBW and extracellular water amount ECW obtained by the CPU 9. And the work area of the CPU 9 is set.

  The measurement processing unit 10 constitutes a body fluid amount measuring means in the present invention, and has the same configuration as the measurement processing unit of the bioelectrical impedance measuring device disclosed in Japanese Patent No. 3636826.

  That is, the measurement processing unit 10 includes a PIO (Parallel Interfence) 71, a measurement signal generator 72, a low-pass filter (hereinafter referred to as LPF) 73, a coupling capacitor 74, and an electrode Hc attached to a predetermined part of a dialysis patient. Output processing circuit comprising: electrodes Hp, Lp, Lc, coupling capacitors 80a, 80b, 90, differential amplifier 81, I / V converter (current / voltage conversion), which are also attached to a predetermined part of dialysis patient X ), LPFs 82 and 92, A / D converters 83 and 93, and input processing circuits including sampling memories 84 and 94.

  A signal generation instruction signal is provided from the CPU 9 to the PIO 71. During the previous measurement time T, the measurement signal generator 72 is supplied with the signal generation instruction signal from the CPU 9 via the PIO 71 at a predetermined period t. Each time, the probe current Ia having the longest linear code (M series) is repeatedly generated a predetermined number of times. The generated probe current Ia is output from the measurement signal generator 72 as a measurement signal. An LPF 73 and a coupling capacitor 74 are connected after the measurement signal generator 72. In the LPF 73, high-frequency noise in the measurement signal is removed, and a DC component in the measurement signal is removed by the coupling capacitor 74. Therefore, the measurement signal from which the high frequency noise and the DC component are removed is given to the surface electrode Hc. The value of the probe current Ia is, for example, about 100 to 800 μA.

  The supply cycle of the signal generator instruction signal coincides with the measurement interval t set using the keyboard 8.

  As shown in FIG. 1, the surface electrode Hc is attached to the back H of the right hand of the dialysis patient X at the time of measurement. Therefore, the measurement signal (probe current Ia) enters the body from the right hand portion of the dialysis patient X. As shown in FIG. 1, the surface electrode Hp is attached to the back of the right hand of the dialysis patient X, and the surface electrode Lp is attached to the back of the right foot. The coupling capacitors 80a and 80b shown in FIG. 2 and the surface electrodes Hp and Lp are respectively connected by coaxial cables. Preferably, as described in Japanese Patent No. 3636826, a shield drive circuit is connected to the shield portion of the coaxial cable so that the potential of the coaxial cable is set to an intermediate potential between the potential of the surface electrode Hp and the potential of the surface electrode Lp. It is desirable to maintain the potential of the shield part. Thereby, the S / N ratio can be increased.

  As shown in FIG. 2, the electrode Hp is connected to one input end of the differential amplifier 81 via a capacitor 80a, and the electrode Lp is connected to the other input end of the differential amplifier 81 via a capacitor 80b. . The differential amplifier 81 detects and amplifies a potential difference between the potential of the surface electrode Hp and the potential of the surface electrode Lp. That is, when the probe current Ia is passed to the dialysis patient X, the differential amplifier 81 detects and outputs the potential difference Vp between the right limb of the dialysis patient X. This voltage Vp is given to the A / D converter 83 via the LPF 82.

  The voltage Vp is a voltage drop due to the bioelectric impedance of the dialysis patient X that can be placed between the surface electrode Hp and the surface electrode Lp. The LPF 82 is provided to remove high frequency noise. The cut-off frequency of the LPF 82 is set lower than ½ of the sampling frequency of the A / D converter 83. Thereby, aliasing noise generated by the A / D conversion process by the A / D converter 83 can be removed.

  Each time the digital conversion signal S / D is supplied from the CPU 3, the A / D converter 83 converts the voltage Vp into a digital signal at a predetermined sampling period, and samples the signal obtained by digitizing the voltage Vp before the sampling period. This is supplied to the memory 84.

  Similarly, the voltage Vc based on the current flowing between the surface electrodes Hc and Lc is output by the I / V converter 91 connected to the electrode Lc via the capacitor 90. That is, the voltage Vc based on the probe current Ia flowing between the right limbs of the dialysis patient X is output from the I / V converter 91, the high frequency noise is removed by the LPF 92, and the voltage Vc is converted into a digital signal by the A / D converter 93. Converted to and output.

  The CPU 9 starts measurement by the measurement processing unit 10 according to the processing program stored in the ROM 12, samples the detection voltages Vp and Vc a predetermined number of times at a predetermined sampling period, and then performs control to stop the measurement. In addition, the CPU 9 sequentially reads out the voltages Vp and Vc that are functions of time stored in the sampling memories 84 and 94, respectively performs Fourier transform, and voltages Vp (f) and Vc (f) that are functions of the frequency. Then, averaging is performed, and bioelectrical impedance Z (f) = {Vp (f) / Vc (f)} for each frequency is calculated. Then, based on the obtained bioelectric impedance Z (f) for each frequency, using the least square method, an impedance locus as shown in FIG. 5 of Japanese Patent No. 3636826 is obtained, and the obtained impedance locus is obtained. From the calculation result, the bioelectrical impedance R0 at the frequency of 0 and the bioelectrical impedance R∞ at the frequency of infinity are calculated, and the intracellular fluid resistance and the extracellular fluid resistance of the dialysis patient X are calculated from the calculation result. Calculate.

  The ROM 12 previously stores the intracellular fluid resistance and extracellular fluid resistance, and the intracellular fluid of the dialysis patient X based on the data such as the height, weight, sex, and age of the dialysis patient X input from the keyboard 8. Formulas for obtaining the extracellular water content ECW and the body water content TBW which is the sum of these are recorded. Then, the CPU 9 calculates the extracellular water content ECW and the body water content TBW based on the intracellular fluid resistance and the extracellular fluid resistance obtained as described above and the data input from the keyboard 8 according to this mathematical formula. To do. Therefore, the CPU 9 and the ROM 12 constitute a calculation means in the present invention.

  Next, a method for actually obtaining the standardized dialysis amount Kt / V based on this embodiment will be described.

  First, prior to measurement, the surface electrodes Hc and Hp are attached to the back of the right hand of the dialysis patient X, and the surface electrodes Lp and Lc are attached to the back of the right foot of the dialysis patient X. Next, human data such as height, weight, sex, and age of the dialysis patient X is input from the keyboard 8. The blood urea nitrogen value before and after dialysis is also input from the keyboard 8.

  The total measurement time T and the measurement time interval t from the measurement start to the measurement end are input from the keyboard 8. Data input from the keyboard 8 is stored in the RAM 11.

  Next, the keyboard 8 is operated, and a signal for starting measurement is generated by the CPU 9. Based on the measurement start signal, a signal generation instruction signal is sent to the measurement signal generator 72 of the measurement processing unit 10. Thereby, the measurement signal generator 72 repeatedly generates the M-sequence probe current Ia a predetermined number of times, and sends the measurement signal to the surface electrode Hc. A measurement signal Ia of 100 to 800 μA flows from the surface electrode Hc through the body of the dialysis patient, and measurement is started. As described above, the voltage from the electrode Hp and the electrode Lp is input to the differential amplifier 82, and the voltage Vp that is the potential difference between the two is detected. On the other hand, the voltage Vc described above is output from the I / V converter. Then, a digital conversion signal is supplied from the CPU 9 to the A / D converters 83 and 93 every sampling period, and the digitized voltage Vp and the digitized voltage Vc are output by the A / D converters 83 and 93. And stored in the sampling memories 84 and 94, respectively.

  The CPU 9 sequentially reads the voltages Vp and Vc, which are voltages of time stored in the sampling memories 84 and 94, and calculates the bioelectric impedance Z (f) before the frequency as described above. Then, the CPU 9 calculates the intracellular fluid resistance and the extracellular fluid resistance of the dialysis patient X based on the bioelectric impedance Z (f) as described above, and further calculates the calculated intracellular fluid resistance. Based on the extracellular fluid resistance, the extracellular water amount ECW and the body water amount TBW are calculated.

  Further, the CPU 9 calculates a standardized dialysis amount Kt / V from the body water amount TBW or the extracellular water amount ECW, the blood urea nitrogen value before and after dialysis, and the dialysis time.

  In this case, when evaluating the first dialysis of the week, the standardized dialysis amount Kt / V is calculated based on the following formula (1).

  In equation (1), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using equation (B) below, TD is Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml).

  K is obtained by the above-described equation (B).

  In addition, when evaluating the second dialysis of the week, a standardized dialysis amount Kt / V is obtained according to the following formula (3).

  In formula (2), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the plasma after the second dialysis in the week It is a value obtained by dividing the urea nitrogen concentration by the two pre-dialysis plasma urea nitrogen concentrations, and UF is the total limit filtration volume (ml) during the second hemodialysis in a week.

  Again, K may be obtained from the above-described equation (D).

  As described above, the standardized dialysis amount Kt / V for the first week and the standardized dialysis amount Kt / V for the second dialysis of the week can be obtained by EPU9, and each hemodialysis can be evaluated.

  When the hemodialysis evaluation method and the hemodialysis evaluation apparatus according to the present embodiment are used, in Expression (1) and Expression (2), V is the body water amount TBW obtained by the bioelectrical impedance method. The accuracy of the standardized dialysis amount Kt / V, which is an index for judging the effect of the dialysis result, can be increased.

  That is, in the hemodialysis evaluation method described in Patent Document 1, the standardized dialysis amount Kt / V for the first weekly hemodialysis is obtained by the above-described formula (A), and the second dialysis weekly hemodialysis is performed. The standardized dialysis amount Kt / V was obtained by the above-described formula (C). In any case, 670 × IBW, that is, 670 times the ideal body weight, was used as the volume V in which urea is distributed in the body of the dialysis patient. This is based on the assumption that in the human body, water is usually 1/13 of the weight of the human body.

  However, as described above, in dialysis patients, the body water content is often considerably higher than in normal conditions due to a decrease in renal function, and the body water content varies greatly due to dialysis. Therefore, when the formula (A) or the formula (C) is used, since the urea distribution body fluid V at the standardized dialysis amount Kt / V is not accurate, the dialysis using the standardized dialysis amount Kt / V is completed with high accuracy. There is a risk that it will not be possible.

  On the other hand, according to this embodiment, the volume V of the urea distribution body fluid energizes the body of the dialysis patient who is currently undergoing dialysis by the bioelectrical impedance method, and the body water content of the dialysis patient X obtained. Since it is based on TBW, the accuracy of the standardized dialysis amount Kt / V can be dramatically increased. Therefore, dialysis management of dialysis patients can be performed more reliably.

  In the above embodiment, the standardized dialysis amount Kt / V was determined according to the above formulas (1) and (2). However, using the following formulas (3) and (4), the initial standardized dialysis amount Kt in the week is used. / V and standardized dialysis amount Kt / V in the second dialysis week may be obtained. In Expressions (3) and (4), V is 3 × ECW, that is, a value three times the extracellular body water content is the volume V of the urea distribution body fluid. This is based on the assumption that the body water content TBW is approximately equal to 3 × ECW. Moreover, when hemodialysis is actually performed with an artificial kidney, urea in extracellular water is more easily removed than intracellular water. Therefore, it may be preferable to use 3 × ECW as the volume V of the urea distribution body fluid.

  In equation (3), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using equation (B) below, where TD is Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml).

  In equation (4), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the plasma after the second dialysis in the week It is a value obtained by dividing the urea nitrogen concentration by the two pre-dialysis plasma urea nitrogen concentrations, and UF is the total limit filtration volume (ml) during the second hemodialysis in a week.

  When measuring the body water content TBW or the extracellular water content ECW by the bioelectrical impedance method, it is preferable to use a multi-frequency bioelectrical impedance method using signals of a plurality of frequencies. This is because a low-frequency signal of about several kHz or less passes through an extracellular fluid such as blood, whereas a relatively high-frequency signal of about several hundred kHz passes through the cell. Accordingly, a probe current of about several kHz is allowed to flow and only the extracellular part is passed, and the extracellular impedance is measured. Based on this, the extracellular water content ECW is obtained, and on the other hand, it is relatively high of several hundred kHz. It is desirable to obtain a body water content TBW by passing a current of a frequency signal through the cell. It is also possible to measure the amount of intracellular water from the difference between the two.

The schematic block diagram which shows the state connected with the dialysis patient and the hemodialysis evaluation apparatus in position embodiment of the hemodialysis evaluation method which concerns on this invention. The block diagram which shows schematic structure of the hemodialysis evaluation apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hemodialysis evaluation apparatus 2 ... Artificial kidney apparatus 3 ... Hemodialysis evaluation apparatus 4 ... Dialyzer 5, 6 ... Dialysis tube 7 ... Drain pipe 8 ... Keyboard 9 ... CPU
10 ... Measurement processing unit 11 ... RAM
12 ... ROM
71 ... PIO
72 ... Measurement signal generator 73 ... LPF
74 ... Capacitor 80a, 80b ... Capacitor 82 ... LPF
83 ... A / D converter 84 ... Sampling memory 90 ... Capacitor 91 ... I / V converter 92 ... LPF
93 ... A / D converter 94 ... Sampling memory

Claims (10)

A hemodialysis evaluation method for evaluating hemodialysis results using a standardized dialysis amount Kt / V in hemodialysis using an artificial kidney,
In the standardized dialysis amount Kt / V, K is the clearance value (ml / mm / kg) of the dialyzer, t is the dialysis time, V is the volume of the urea distribution body fluid, and the standardized dialysis amount Kt / V is In determining, the hemodialysis evaluation method is characterized in that the volume V of the urea distribution body fluid is measured using a bioelectrical impedance method.   The hemodialysis evaluation method according to claim 1, wherein the volume V of the urea distribution body fluid is a body water amount TBW measured using a bioelectrical impedance method. In evaluating the initial dialysis result in the week using the standardized dialysis dose Kt / V, the clearance value is used as K on the right side of the following formula (1), the dialysis time is used as TD, and the bioelectrical impedance method is used as TBW. The hemodialysis evaluation method according to claim 2, wherein the measured body water content is used.

In the formula (1), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using the following formula (B). Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml). In order to evaluate the second hemodialysis result in the week based on the standardized dialysis amount Kt / V, the bioelectrical impedance method uses the clearance value as K on the right side of the following formula (2), the dialysis time as TD, and TBW. The hemodialysis evaluation method according to claim 2, wherein the body water content measured by using is used.

In equation (2), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the plasma after the second dialysis in the week The urea nitrogen concentration is a value obtained by dividing the concentration of urea nitrogen by two pre-dialysis plasma urea nitrogen concentrations, and UF is the total limit filtration volume (ml) during the second hemodialysis in a week.   The hemodialysis evaluation method according to claim 1, wherein the volume V of the urea distribution body fluid is an extracellular water content ECW × 3 measured using a bioelectrical impedance method. In evaluating the initial dialysis result in the week based on the standardized dialysis dose Kt / V, the clearance value was measured as K on the right side of the following formula (3), the dialysis time was measured as TD, and the bioelectrical impedance method was measured as ECW. The method for evaluating hemodialysis according to claim 5, wherein the amount of extracellular body fluid is used.

In equation (3), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, and is a numerical value obtained using equation (B) below, where TD is Dialysis time (hr), R is the value obtained by dividing the plasma urea nitrogen concentration after the initial dialysis in the week by the pre-dialysis plasma urea nitrogen concentration in the week, and UF is the total limit filtration volume during the first hemodialysis in the week. (Ml). In evaluating the second hemodialysis result in the week using the standardized dialysis dose Kt / V, the clearance value is used as K on the right side of the following formula (4), the dialysis time is used as TD, and the bioelectrical impedance method is used as ECW. The method for evaluating hemodialysis according to claim 5, wherein the amount of extracellular water measured is used.

In equation (4), K on the right side is the dialyzer clearance (ml / min / kg) when the change in urea distribution volume is ignored, TD is the dialysis time (hr), and R is the plasma after the second dialysis in the week The urea nitrogen concentration is a value obtained by dividing the concentration of urea nitrogen by two pre-dialysis plasma urea nitrogen concentrations, and UF is the total limit filtration volume (ml) during the second hemodialysis in a week.   The hemodialysis evaluation method according to any one of claims 1 to 7, wherein the bioelectrical impedance method is a multi-frequency bioelectrical impedance method. A body fluid volume measuring means for measuring body water volume TBW or extracellular water volume ECW of a dialysis patient using a bioelectrical impedance method;
Input means for inputting blood urea nitrogen level and dialysis time before and after dialysis of a dialysis patient;
Calculation means for obtaining the standardized dialysis amount Kt / V from the blood urea nitrogen value before and after dialysis inputted from the input means, the dialysis time, and the body water amount TBW or the extracellular water amount ECW obtained by the body fluid amount measuring means. And a hemodialysis evaluation apparatus.   The hemodialysis evaluation apparatus according to claim 9, wherein the body fluid amount measuring means is a device for measuring a body water amount TBW or an extracellular fluid amount ECW by a multi-frequency bioelectrical impedance method.

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